Carbon Dot-Driven phase transition in coaxial Wet-Spun PVDF fibers for wearable piezoelectric energy harvesting

Flexible piezoelectrics are pivotal for self-powered wearable systems, yet low-dimensional materials like PVDF fibers suffer from inefficient β-phase crystallization and limited charge transport. Here, coaxial wet-spun polyvinylidene fluoride (PVDF) fibers integrated with carbon quantum dots (CDs) overcome these limitations via solvent-nonsolvent phase separation and mechanical stretching. A 3 wt% CDs doping induces 75.96 % β-phase content through interfacial hydrogen bonding, achieving a high piezoelectric coefficient (d 33 of 28 pC/N) and output performance of 19.4 V and 0.2 μA, which is 86.7 % surpassing pristine PVDF(15 pC/N), and Under optimal experimental conditions, the peak voltage and current can reach up to 31 V and 0.2 μA. Cyclic durability tests (3 Hz, 20 N, 1000 cycles) confirm excellent stability with > 90 % performance retention. Practical applications highlight rapid capacitor charging (5 V in 30 s) and the ability to power nine LEDs. Additionally, bending sensitivity (3.6 V at 60°) and motion sensing (9 V for arm bending) validate its adaptability for wearable electronics and IoT applications, offering a scalable strategy for high-performance flexible energy harvesters.